Ptolemy was a Greek astronomer, mathematician, geographer, astrologer, and poet who lived in Roman Egypt during the 2nd century CE. He is best known for his work on astronomy, which includes the Almagest, a treatise on the apparent motions of the stars and planetary paths, as well as the Handy Tables, a star catalog that was used by astronomers for over 1500 years. He also wrote on geography, optics, music theory, and astrology.
